The metastasis of melanoma and carcinoma to distant sites often portends a poor prognosis (1). Assessment of primary and/or metastatic melanoma and carcinoma has been addressed in the new American Joint Committee on Cancer (AJCC) staging criteria (2, 3). The staging system, however, does not accurately take into account the disease progression events, particularly ongoing systemic metastasis, at the time patients are seen. The detection of melanoma or carcinoma cells in circulation is important in assessing tumor progression and potential for metastasis.
To date, only a limited number of tumor-associated markers have been identified that are absent in healthy cells but produced in melanoma or carcinoma cells. Heterogeneity of the expression of tumor genes and variable performance of the assays have posed major problems for detection of circulating tumor cells (CTCs) in blood. The clinical utility of molecular detection of circulating tumor cells in blood continues to be debated, mostly because of inconsistency among the previous findings, indicating the necessity for performing careful characterizations of these tests.
Melanoma and carcinoma patients are candidates for adjuvant therapy because of their high risk of disease recurrence after complete surgical resection. However, no current assays can accurately predict the survival of patients receiving neoadjuvant or adjuvant biochemotherapy (BC).